Multiple choice problems in nuclear chemistry.

1. As the temperature of a sample of a radioactive element decreases, the half-life will
A. decrease
B .increase
C. remain the same
D. depends on the nucleus
E. none of the above

2. In a fusion reaction, reacting nuclei must collide. Collisions between two nuclei are difficult to achieve Because the nuclei are
A. both negatively charged and repel each other
B. both positively charged and repel each other
C. oppositely charged and attract each other
D. oppositely charged and repel each other
E. none of the above

3. Heavy water and graphite are two exs of materials that are can be used in a nuclear reactor to slow down neutrons. These materials are called
1.fuels
2.shields
3.coolants
4.moderators
5.none of the above

4.Which reaction illustrates fusion?
A.1H2 + 1H2 à 2He4
B.0n1 + 13Al27 à 11Na24 + 2He4
C.13Al27 + 2He4 à 15P30 + 0n1
D.7N14 + 2He4 à 1H1 + 8O17
E.all of the above

5.Compared to chemical reactions, nuclear reactions produce:
i.proportionately far less energy
ii.fewer changes in the nucleus
iii.proportionately far more energy
iv.different states
v.none of the above